According to this question, Mary is trying to view 5 pollen grains under her microscope. She found out that the 5 pollen grains each with a diameter of 0.3mm could fit along the diameter of the field of view of her microscope.
This means that the diameter of the field of view of Mary's microscope can be calculated as follows:
Diameter of each pollen × no. of pollen that fit in
= 0.3mm × 5
= 1.5mm
Hence, the diameter of the field of view of Mary's microscope is 1.5mm.
